A fluidized bed apparatus for the production and treatment of granules and a method for its operation is provided. The fluidized bed apparatus includes an entry chamber through which a gas is designed to flow upwards; a fluidization chamber for fluidizing the material located above the entry chamber; pivotal slats located between the entry chamber and the fluidization chamber; and a nozzle arm located in the chamber below the slats with a nozzle line ending in a nozzle which is directed into the fluidization chamber through cutouts in the slats and extends partly into the fluidization chamber. The fluidized bed apparatus has rigid nozzle arms and lines which are easily jacketed for heating and cooling applications.